1. Field of the Invention
The present invention relates to a vibration measuring method, a balance correcting method, and an information recording and/or reproducing apparatus that can be preferably used in a magnetic and electric characteristic inspection apparatus for the servo track writer, the head, the head gimbal assembly, and the head stack assembly of a hard disc drive as well as in a magnetic or electric characteristic inspection apparatus, and the like for a hard disc itself and further also can be preferably used in an inspection and manufacturing apparatus for an optical or magneto-optical recording head and an optical or magneto-optical recording disc.
2. Description of the Related Art
FIG. 1 shows an arrangement of a conventional information recording/reproducing apparatus in which a spindle motor 102 is fixed on a base 101 to drive a disc D. A head H is mounted at the extreme end of the rotating shaft of a rotary type positioning controller 103 through a head fixing jig 104. The rotary type positioning controller 103 is supported by an X-stage 105 that is free to reciprocate on the base 101 in an X-axis direction shown by an arrow.
The distance between the center of the disc D and the center of rotation of the head H can be arbitrarily adjusted by moving the X-stage 105. When a disc replacing job is executed, the rotary type positioning controller 103 moves in a direction where it is apart from the disc D and the spindle motor 102.
The drive unit of the spindle motor 102 I s composed of a motor unit 102a for driving the spindle motor 102 and an encoder 102b for detecting a rotational angle and outputting one pulse each one rotation. As shown in FIG. 2, the rotation of the spindle motor 102 is controlled through a spindle driver 112 in response to a command signal from a CPU 111. The rotational shaft of the spindle motor 102 holds the disc D by a clamp 107 on a clamp base 106 and is rotatably supported by an air bearing 108.
The drive unit of the rotary type positioning controller 103 also is composed of a motor unit 103a and an encoder 103b for detecting a rotational angle and connected to the CPU 111 through a servo controller 113.
When information is recorded and reproduced, the X-stage 105 is moved in the X-axis direction from the position shown in FIG. 1 to cause the rotary type positioning controller 103 to approach the spindle motor 102, the rotary type positioning controller 103 is rotated by driving the motor unit 103a, the head H is positioned on an arbitrary track on the disc D, and then the spindle motor 102 starts to be driven.
When the vibration of the spindle motor 102 is measured and the balance thereof is corrected, an A/D converter 114, an acceleration sensor 115 such as an acceleration sensor or the like and the amplifier 116 of the acceleration sensor 115 are mounted on the base 101 and connected to the CPU 111 through a PC 111a. As shown in FIG. 1, the acceleration sensor 115 is mounted in the vicinity of the spindle motor 102.
The CPU 111 issues a command for starting the rotation of the spindle motor 102 and thereafter starts measurement by the acceleration sensor 115. The encoder 102b of the spindle motor 102 generates one pulse per one rotation and determines a position of the spindle motor 102 where its rotation is unbalanced. This unbalance is corrected by a known method.
According to the above conventional technology, however, the acceleration sensor and the like must additionally be mounted on the apparatus as described above to measure vibration and to correct balance.
The present invention, which was made in view of the unsolved problems of the conventional technology, is to a provide a vibration measuring method, a balance correcting method, and information recording and/or reproducing apparatus capable of measuring the unbalance of rotating units such as a spindle motor and the like at a pinpoint accuracy and correcting it without the need of an accelerator sensor and the like.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.